It sounds pretty kinky, like it should be playing at a gay film festival: A brother and sister — twins, no less — both find themselves falling romantically for a charming hipster.

Except that the comedy “I Love You Both” isn’t actually about sex or romance.

No, this home-grown effort by real-life twins Doug and Kristin Archibald — they co-wrote the script, play siblings onscreen, and Doug directed (plus, they cast their own mother as their characters’ mom) — is about something trickier, something that maybe only twins would truly understand.

As they approach their 28th birthdays, Krystal and Donny are crazily co-dependent. They still live together in a tiny apartment. They share a dog. Both are a bit antisocial — or at least socially inept. Small wonder that they’ve always been each other’s best friend.

Oh, they make a stab at a life outside their little insular world. Krystal works for a software company and recently broke up with a co-worker. Donny is a keyboardist dreaming of a concert career and marking time by teaching piano to tone-deaf kids.

But basically neither can imagine a life independent of the other.

Enter Andy (Lucas Neff), a laid-back, genuinely nice elementary school teacher who has a history with both men and women.

Initially Krystal and Donny accept Andy’s friendship at face value…except that both are nurturing a flame for their new bud.

Eventually that tension will force them to begin carving out individual lives.

The film’s oddball sense of humor — filled with eye rolling at the relationship minefield — sometimes pushes too hard. But Kristin Archibald, making her acting debut, proves adept at selling an infectious blend of dweeb sexiness and sardonic glumness. She might have an acting career ahead of her.

Brother Doug is less photogenic and not quite so compelling a screen presence, but his behind-the-scenes work is top notch.